'use client';

import { useState, useMemo } from "react";
import AdminSidebar from "@/app/components/AdminSidebar";
import CourseRegistrationModal from "./CourseRegistrationModal";
import ChevronDownSvg from "@/app/svgs/chevrondownsvg";
import { MOCK_COURSES, MOCK_CURRENT_USER, type Course } from "./mockData";

export default function AdminCoursesPage() {
  const [courses, setCourses] = useState<Course[]>(MOCK_COURSES);
  const [isModalOpen, setIsModalOpen] = useState(false);
  const [editingCourse, setEditingCourse] = useState<Course | null>(null);
  const [currentPage, setCurrentPage] = useState(1);
  
  const totalCount = useMemo(() => courses.length, [courses]);
  
  const ITEMS_PER_PAGE = 10;
  const sortedCourses = useMemo(() => {
    return [...courses].sort((a, b) => {
      // 생성일 내림차순 정렬 (최신 날짜가 먼저)
      return b.createdAt.localeCompare(a.createdAt);
    });
  }, [courses]);
  
  const totalPages = Math.ceil(sortedCourses.length / ITEMS_PER_PAGE);
  const paginatedCourses = useMemo(() => {
    const startIndex = (currentPage - 1) * ITEMS_PER_PAGE;
    const endIndex = startIndex + ITEMS_PER_PAGE;
    return sortedCourses.slice(startIndex, endIndex);
  }, [sortedCourses, currentPage]);

  const handleSaveCourse = (courseName: string, instructorName: string) => {
    if (editingCourse) {
      // 수정 모드
      setCourses(prev => prev.map(course => 
        course.id === editingCourse.id
          ? { ...course, courseName, instructorName }
          : course
      ));
    } else {
      // 등록 모드
      const newCourse: Course = {
        id: String(Date.now()),
        courseName,
        instructorName,
        createdAt: new Date().toISOString().split('T')[0],
        createdBy: MOCK_CURRENT_USER,
        hasLessons: false, // 기본값: 미포함
      };
      setCourses(prev => [...prev, newCourse]);
    }
    setIsModalOpen(false);
    setEditingCourse(null);
  };

  const handleRowClick = (course: Course) => {
    setEditingCourse(course);
    setIsModalOpen(true);
  };

  const handleModalClose = () => {
    setIsModalOpen(false);
    setEditingCourse(null);
  };

  const handleRegisterClick = () => {
    setEditingCourse(null);
    setIsModalOpen(true);
  };

  return (
    <div className="min-h-screen flex flex-col bg-white">
      {/* 메인 레이아웃 */}
      <div className="flex flex-1 min-h-0 justify-center">
        <div className="w-full max-w-[1120px] flex min-h-0">
          {/* 사이드바 */}
          <div className="px-8 flex">
            <AdminSidebar />
          </div>
          {/* 메인 콘텐츠 */}
          <main className="flex-1 min-w-0 bg-white">
            <div className="h-full flex flex-col">
              {/* 제목 영역 */}
              <div className="h-[100px] flex items-center">
                <h1 className="text-[24px] font-bold leading-[1.5] text-[#1b2027]">
                  교육과정 관리
                </h1>
              </div>

              {/* 헤더 영역 (제목과 콘텐츠 사이) */}
              <div className="pt-2 pb-4 flex items-center justify-between">
                <p className="text-[15px] font-medium leading-[1.5] text-[#333c47] whitespace-nowrap">
                  총 {totalCount}건
                </p>
                <button
                  type="button"
                  onClick={handleRegisterClick}
                  className="h-[40px] px-4 rounded-[8px] bg-[#1f2b91] text-[16px] font-semibold leading-[1.5] text-white whitespace-nowrap hover:bg-[#1a2478] transition-colors"
                >
                  등록하기
                </button>
              </div>

              {/* 콘텐츠 영역 */}
              <div className="flex-1 pt-2 flex flex-col">
                {courses.length === 0 ? (
                  <div className="rounded-lg border border-[#dee1e6] bg-white min-h-[400px] flex items-center justify-center">
                    <p className="text-[16px] font-medium leading-[1.5] text-[#333c47]">
                      등록된 교육과정이 없습니다.
                      <br />
                      과목을 등록해주세요.
                    </p>
                  </div>
                ) : (
                  <div className="rounded-[8px]">
                    <div className="w-full rounded-[8px] border border-[#dee1e6] overflow-visible">
                      <table className="min-w-full border-collapse">
                        <colgroup>
                          <col />
                          <col />
                          <col style={{ width: 140 }} />
                          <col />
                          <col style={{ width: 120 }} />
                        </colgroup>
                        <thead>
                          <tr className="h-12 bg-gray-50 text-left">
                            <th className="border-r border-[#dee1e6] px-4 text-[14px] font-semibold leading-[1.5] text-[#4c5561]">교육과정명</th>
                            <th className="border-r border-[#dee1e6] px-4 text-[14px] font-semibold leading-[1.5] text-[#4c5561]">강사명</th>
                            <th className="border-r border-[#dee1e6] px-4 text-[14px] font-semibold leading-[1.5] text-[#4c5561]">생성일</th>
                            <th className="border-r border-[#dee1e6] px-4 text-[14px] font-semibold leading-[1.5] text-[#4c5561]">등록자</th>
                            <th className="px-4 text-center text-[14px] font-semibold leading-[1.5] text-[#4c5561]">강좌포함여부</th>
                          </tr>
                        </thead>
                        <tbody>
                          {paginatedCourses.map((course) => (
                            <tr
                              key={course.id}
                              className="h-12 cursor-pointer hover:bg-[#F5F7FF] transition-colors"
                              onClick={() => handleRowClick(course)}
                            >
                              <td className="border-t border-r border-[#dee1e6] px-4 text-[13px] leading-[1.5] text-[#1b2027] whitespace-nowrap">
                                {course.courseName}
                              </td>
                              <td className="border-t border-r border-[#dee1e6] px-4 text-[13px] leading-[1.5] text-[#1b2027] whitespace-nowrap">
                                {course.instructorName}
                              </td>
                              <td className="border-t border-r border-[#dee1e6] px-4 text-[13px] leading-[1.5] text-[#1b2027] whitespace-nowrap">
                                {course.createdAt}
                              </td>
                              <td className="border-t border-r border-[#dee1e6] px-4 text-[13px] leading-[1.5] text-[#1b2027] whitespace-nowrap">
                                {course.createdBy}
                              </td>
                              <td className="border-t border-[#dee1e6] px-4 text-left text-[13px] leading-[1.5] text-[#1b2027] whitespace-nowrap">
                                {course.hasLessons ? (
                                  <div className="inline-flex items-center justify-center h-[20px] px-[4px] rounded-[4px] bg-[#ecf0ff]">
                                    <span className="text-[13px] font-semibold leading-[1.4] text-[#384fbf] whitespace-nowrap">
                                      포함
                                    </span>
                                  </div>
                                ) : (
                                  <div className="inline-flex items-center justify-center h-[20px] px-[4px] rounded-[4px] bg-[#f1f3f5]">
                                    <span className="text-[13px] font-semibold leading-[1.4] text-[#4c5561] whitespace-nowrap">
                                      미포함
                                    </span>
                                  </div>
                                )}
                              </td>
                            </tr>
                          ))}
                        </tbody>
                      </table>
                    </div>
                  </div>
                )}

                {/* 페이지네이션 - 10개 초과일 때만 표시 */}
                {courses.length > ITEMS_PER_PAGE && (() => {
                  // 페이지 번호를 10단위로 표시
                  const pageGroup = Math.floor((currentPage - 1) / 10);
                  const startPage = pageGroup * 10 + 1;
                  const endPage = Math.min(startPage + 9, totalPages);
                  const visiblePages = Array.from({ length: endPage - startPage + 1 }, (_, i) => startPage + i);

                  return (
                    <div className="pt-8 pb-[32px] flex items-center justify-center">
                      <div className="flex items-center justify-center gap-[8px]">
                        {/* First (맨 앞으로) */}
                        <button
                          type="button"
                          onClick={() => setCurrentPage(1)}
                          aria-label="맨 앞 페이지"
                          className="flex items-center justify-center rounded-[1000px] p-[8.615px] size-[32px] text-[#333c47] disabled:opacity-40"
                          disabled={currentPage === 1}
                        >
                          <div className="relative flex items-center justify-center w-full h-full">
                            <ChevronDownSvg width={14.8} height={14.8} className="rotate-90 absolute left-[2px]" />
                            <ChevronDownSvg width={14.8} height={14.8} className="rotate-90 absolute right-[2px]" />
                          </div>
                        </button>

                        {/* Prev */}
                        <button
                          type="button"
                          onClick={() => setCurrentPage((p) => Math.max(1, p - 1))}
                          aria-label="이전 페이지"
                          className="flex items-center justify-center rounded-[1000px] p-[8.615px] size-[32px] text-[#333c47] disabled:opacity-40"
                          disabled={currentPage === 1}
                        >
                          <ChevronDownSvg width={14.8} height={14.8} className="rotate-90" />
                        </button>

                        {/* Numbers */}
                        {visiblePages.map((n) => {
                          const active = n === currentPage;
                          return (
                            <button
                              key={n}
                              type="button"
                              onClick={() => setCurrentPage(n)}
                              aria-current={active ? 'page' : undefined}
                              className={[
                                'flex items-center justify-center rounded-[1000px] size-[32px]',
                                active ? 'bg-[#ecf0ff]' : 'bg-white',
                              ].join(' ')}
                            >
                              <span className="text-[16px] leading-[1.4] text-[#333c47]">{n}</span>
                            </button>
                          );
                        })}

                        {/* Next */}
                        <button
                          type="button"
                          onClick={() => setCurrentPage((p) => Math.min(totalPages, p + 1))}
                          aria-label="다음 페이지"
                          className="flex items-center justify-center rounded-[1000px] p-[8.615px] size-[32px] text-[#333c47] disabled:opacity-40"
                          disabled={currentPage === totalPages}
                        >
                          <ChevronDownSvg width={14.8} height={14.8} className="-rotate-90" />
                        </button>

                        {/* Last (맨 뒤로) */}
                        <button
                          type="button"
                          onClick={() => setCurrentPage(totalPages)}
                          aria-label="맨 뒤 페이지"
                          className="flex items-center justify-center rounded-[1000px] p-[8.615px] size-[32px] text-[#333c47] disabled:opacity-40"
                          disabled={currentPage === totalPages}
                        >
                          <div className="relative flex items-center justify-center w-full h-full">
                            <ChevronDownSvg width={14.8} height={14.8} className="-rotate-90 absolute left-[2px]" />
                            <ChevronDownSvg width={14.8} height={14.8} className="-rotate-90 absolute right-[2px]" />
                          </div>
                        </button>
                      </div>
                    </div>
                  );
                })()}
              </div>
            </div>
          </main>
        </div>
      </div>
      <CourseRegistrationModal
        open={isModalOpen}
        onClose={handleModalClose}
        onSave={handleSaveCourse}
        editingCourse={editingCourse}
      />
    </div>
  );
}